Standardization of 0.1 M Silver Nitrate Solution
Introduction
Silver nitrate (AgNO₃) is a strong oxidizing agent commonly used in analytical chemistry as a titrant for the determination of halides, cyanides, and other anions. The standardization of a 0.1 M silver nitrate solution is crucial to ensure accurate results in titrimetric analysis. In this article, we will discuss the procedure for standardizing a 0.1 M silver nitrate solution using sodium chloride (NaCl) as a primary standard.
Theory
The reaction between silver nitrate and sodium chloride is as follows:
AgNO₃ + NaCl → AgCl + NaNO₃
The reaction is quantitative, meaning that one mole of silver nitrate reacts with one mole of sodium chloride to form one mole of silver chloride and one mole of sodium nitrate.
Materials
- 0.1 M silver nitrate solution (AgNO₃)
- Sodium chloride (NaCl, primary standard)
- Distilled water
- Burette
- Conical flask
- Pipette
Procedure
Preparation of Sodium Chloride Solution
- Weigh accurately about 0.5 g of sodium chloride (NaCl) and transfer it to a 100 mL conical flask.
- Add about 50 mL of distilled water to the flask and stir until the sodium chloride is completely dissolved.
- Transfer the solution to a 100 mL volumetric flask and make up to the mark with distilled water.
Standardization of Silver Nitrate Solution
- Pipette 25.00 mL of the sodium chloride solution into a conical flask.
- Add 2-3 drops of potassium chromate indicator (optional, but recommended to detect the end point).
- Titrate the sodium chloride solution with the 0.1 M silver nitrate solution until a faint red precipitate of silver chromate appears.
- Record the volume of silver nitrate solution required to reach the end point.
- Repeat the titration at least three times to ensure consistency.
Calculation
- Calculate the molarity of the silver nitrate solution using the following formula:
Molarity of AgNO₃ = (Weight of NaCl / Molar mass of NaCl) / (Volume of AgNO₃ required x Molarity of NaCl)
where:
- Weight of NaCl = 0.5 g
- Molar mass of NaCl = 58.44 g/mol
- Molarity of NaCl = 0.1 M
- Volume of AgNO₃ required = average of the three titrations
Example Calculation
Let's say the average volume of silver nitrate solution required is 24.50 mL.
Molarity of AgNO₃ = (0.5 g / 58.44 g/mol) / (24.50 mL x 0.1 M) = 0.104 M
Thus, the 0.1 M silver nitrate solution is standardized to be 0.104 M.
Conclusion
The standardization of a 0.1 M silver nitrate solution is a crucial step in ensuring accurate results in titrimetric analysis. By following the procedure outlined above, the molarity of the silver nitrate solution can be determined with high precision. This standardized solution can then be used as a titrant for the determination of halides, cyanides, and other anions in various analytical applications.
